Method of seasoning wood



Patent ed a.. 16, 1928.

UINITEDSTATES PATENT OFFICE.

FORREST STREATOR SHINN, 0F GALESBURG, ILLINOIS.

mn'rnonor SEASONING woon.

. No Drawing. 7 i

The present invention relates to methods of seasoning material such as wood in the form of lumber, etc.

The general object of the invention is to provide a new and improved method particularly adapted for therapid seasoning of wood or other material which is afterward to be impregnated with some preservative.

I tended for use in the seasoning of green wood, that is, wood which has been recently cut, but it is not limited to that use. Fresh cut or green woodcontai ns in its pores a large amount of moisture which renders difficult the impregnation of the .wood with a preservative; and my method hereinafter described, permitsv the rapidrem'oval of a large proportion of such moisture from the wood, and leaves the wood in a condition to be readily impregnated with a preservative in any suitable. and well-known manner.

prises my invention may be carried out with a retort, preferably of the horizontal cylin- 3 drical type, usually found in wood treating plants. In connection with the retort there should beprovided means such as a steam boiler .for' supplying steam to the retort; means such as 'a condenserand a vacuum 5 pump for exhausting the retort to a pressure approaching a vacuum, say 28.5 or 29 inches of mercury; and an air-compressor by which compressed air may be furnished to the retort to raise the pressure in thelatter 40 considerably above atmospheric pressure,

say to 80 lbs. per squareinch. The arrangement of piping connecting the boiler, the con denser and vacuum pump, and the air-compressor to the retort, and the arrangement of 5 control valve in such piping will be obvious to one skilled in the art.

With such apparatus as that above ;mentioned, my improved method of seasoning wood may be successfully carried out in the following manner-upon wood arranged in the usual Way in a closed retort:

by subjecting it to a'bat h of steam at a presposts, poles, piles, railroad ties,

=sure in the'la'tter is restored to atm (a) The wood to be treated is first heated- Application am March 2a, 1927. Serial m1.- 177,473.

sure considerably above atmospheric pressure, which heats thewood and its water content to a temperature considerably hi her than 212 degrees Fahrenheit, but not igh enough to in any manner injure the wood.

A steam pressurej'of 20 lbs. pensquare inch maintained in'the retort for a enod of one hour has been found to be satis actory. During this steam treatment any water condensed from the steam is preferably drained from the retort so as not to permit its reaching the timbers.

(6) At the end of the steaming period, the

supply of steam is cut off and the steam inthe retort is allowed to blow ofi to atmospheric pressure, whereupon the retort is immediate- 1y subjectedto a high vacuum, say 28.5 or 29 inches of mercury in a manometer,

through themedium of a'condenser and vacpump connected .to the'retort." Owing uum to the fact that the boiling point of water at this. reduced pressure in the retort is *far below the temperature to which the wood has been heated by the previoussteam treatment, a considerable part of the watercontent of- I the wood comes out of the latter" in the-form The method of seasoning wood which comparent from observations of the well of the condenser.

(c) The condenser and vacuum pump are then shut ofl from the retort and theai-r reser1c pressure, after which it is increase considerablyabove atmospheric pressure by forcing air into the retort by means of an air-compressor. The wood being treated in the retort is held under'such air pressure for a length of time suflicient, in the opinion of the operator, to make sure thatthe compressed air in the retort has worked thoroughly into the cells of the wood being treated. In prac-- ties, with one kind of wood, it has been found that an air pressure of 80 lbs. er square inch maintained for one hour is satisfactory. The

air-com ressor .is then cut ofi from the retort, an the pressure within-the latteris al-' 'lowed to quickly exhaust to atmospheric pressure, which results in the expulsion of water from the wood due to the action-of the the steam to a temperature considerably air at high pressure in escaping from the pores of the latter. 7

- (d) Steam is then again supplied to the retort, as in the first step of the method, and the woodbeing'treated is again heated by higher than the boiling point of water at atmospheric pressure; It has been found that this second steam treatment also may ad,

vantageously be carried on with steam at lbs. pressure foraperiod of one hour. 1

(e) lhe retort is then cut oil from connectionwith the source of steam supply and is pump, as in thesecond step of the method.

from the retort and be condenser. y Ordinarily, at the conclusion'of the five allowed to exhaust to atmospheric pressure; and again the retort is subjected to a high vacuum'byme'ans of a condenser and vacuum The proper duration of this second vacuum.

treatment may be determined in the same 20.

manner as above mentioned, namely, by ob serving-when water vapor ceases tocome condensed 311- the steps of the method above described,- the wood has been seasoned sufficiently to permit its proper impregnation by any suitable 'im-,

pregnating fluid. But if further seasoning is considered necessary or desirable, the

wood-may again be. subjected to highair.

- pressure followed by a quick release to atmospheric pressure, another heating by mannerfabove described.

steam, and another vacuum treatment, in the Wheil my method of seasoning is to lbe followed by the so-called full cell process of impregnating wood with a 'preservativ'e,'it

- may be restored to atmospheric pressurebe-'- fore the wood is treated with reservative'. V

i It has been found in practlcd-that green will be foundconvenient to admit the revservative-to the retort at the end of one o the 4 vacuum treatment-s above described, without breakingthe vacuum. It is to be understood, however, that my method of seasoning may 'be-vfollowed by any well-known method of impre atin'g'wood with a preservative; and that i desired the pressure within the retort "wood, after having been subjected toi'my method of'seasoning above described, is actually capable of absorbing a preservative 'materiaI to an. extent by volume which. compares favorably with the. absorption which is obtained in the case ofwood of a similar kind in large part to thesubjecting of the woodto high air pressure after the first steamand vacuum treatments and before the second.

which has "been air-seasoned in the; usual manner. I attribute such result as being due steam and vacuum treatments. However, in

' some cases, it may be found satisfactorgoto discontinue the seasoning treatment a ve described at the end of the third step, that is,

after the'wood'fhas been subjected merely to a steam bath, hi'gh vacuum'and high air pres proximate direct treatment with steam at approxisure followedby release to atmospheric pressure. To one skilled inthe art other modifications'of my method of seasoning wood may i be obvious without departingfrom the scope of my invention. f

I claim i v 1. A method ofseasoning wood character.- i'zed'by the facts that'the' woodis first subjected to steam and vacuum treatments, is then subjected toair, pressure considerably higher than atmospheric pressure followed by quick release 'to atmospheric pressure, and

. is then again subjected to steam and vacuum treatments. v 2. A method of seasoning wood characterized bythe facts that the wood is first heated with steam, is then subjectedlto a vacuum treatment, is then subjectedto air pressure" considerably higher than atmospheric pressure followed by a quick release to atmospheric pressure, is then again heated-with uum treatment.

ized by the facts that the wood is first heated 3. A method of seasoningiwood character steam, and is then again subjected to a vac with steam at a pressure considerably higher than atmospheric pressure, is'then subjected to a vacuum treatment, is then subjected to air pressure considerably higher than atmospheric pressure followed byquick release to atmospheriepressure, is then again heated with steam at a pressure considerably higher than atmospheric pressure, and isthen again.

subjected to a vacuum treatment,

4. A method of seasoning wood character-. ized by the facts that the wood is first maintained. surrounded for a considerable period of time with'steam ata pressure considerably higher than atmospheric pressure, is then subjected fora conslderable period of time to' a vacuum treatment,is then maintained surroundedfor a considerable periodof time" with compressed air at a pressure considerably higher than atmospheric pressure, said pressure being then quickly reduced to at-' mosphericpressure, is then again maintained for a considerable period of time surrounded natmosphenc pressure, and is then again' for a consi erable period of time subjected to a vacuum treatment. i I

- 5. A method of seasoning wood character ized by the facts that the wood is first heated for approximately one hour by direct treat. ment with steamat a pressure of approximately twenty pounds per square inch, is then subjected or approximately one'hour vto avacuum treatment, is then subjected for approximately one hour to direct treatment a with compressed air at a pressure of a' y eighty pounds per square inc said pressure being then quickly reduced to atmospheric pressure is ther again for a riod of approximatelyone hour heated b;

ha steam at a pressure considerably higher l t a mately twenty pounds per square inch, and is then again for approximately one hour subjected to a vacuum treatment.

6. A method of seasoning wood character- 5 ized by the facts that the wood is first heated by treatment with steam at a pressure considerably higher than atmospheric pressure, is then immediately subjected to a vacuum treatment, and is then subjected to treatment with compressed air at a pressure considerably higher than atmospheric pressure followed by quick release to atmospheric pressure. a

In testimony whereof, I have aflixed my signature to this specification.

FORREST STREATORVSHINN. 

